This invention relates to washing machines having impellers to be rotated unidirectionally, and particularly to washing machines with dashers having spiral surfaces to be rotated at relatively high speeds for circulating clothes radially therefrom.
Early manual washing machines and most of the subsequent electric washing machines have used reciprocating agitators for moving clothes back and forth in water to clean them. Some of the early agitators, or dollies, had one or more downwardly extending pegs that contacted the clothes and moved them in a reciprocating motion within the water and against the corrugated inside surfaces of the tubs of the washers. The clothes were generally merely being rotated reciprocally as a single body attached to a crank. The type of agitators that have become most widely accepted for electric washing machines have three or four long vertical vanes, and by reciprocating the agitators, the vanes tend to circulate articles of clothing to wash them uniformly. However, when the washing machines are moderately or heavily loaded, the articles bunch and, as in the washers using the old dollies, follow the agitator as if attached to a crank. When the clothes are bunched, they are not washed uniformly and are worn unnecessarily.
The reciprocating rotation of the agitators, rather than unidirectional rotation, is considered to be necessary to cause the required rubbing of the clothes for cleaning and to prevent the clothes from bunching and whirling with the agitators. The apparent necessity for having reciprocation of the agitators requires quite complicated arrangements of gears between the driving motors and the agitators. The gear arrangements are expensive and are subject to wear because of the usual shocks accompanying reciprocating motion.
While the present washing machines that use reciprocating agitators were being developed and improved, development work also progressed on washing machines using unidirectionally driven impellers. One of the later washing machines of this type is shown in U.S. Pat. No. 3,233,436, issued to the present inventor on Feb. 8, 1966. The impellers used in the washing machines described in that patent have relatively low profiles, and the bottoms of the tubs had cavities about the impellers. Water was first driven from the impellers into the cavities to be redirected into columns to prevent the water and wash from being whirled excessively by the impellers. As with other washing machines having unidirectionally driven impellers, the impellers and the tubs were designed especially to decrease the tendency for wash to be collected together and to be whirled with the impellers. Although some of the better washing machines using unidirectionally driven impellers would do fairly well in preventing entanglement and in circulating the clothes to clean them uniformly, none of them apparently reached high enough standards in these respects to be widely accepted in spite of their economical and long-lasting driving apparatus.
The impellers in the patent to which reference has been made above have pockets between ridges for slinging water radially outwardly into cavities that surround the impellers. The ends of the ridges between the pockets are curved in a direction opposite to the direction of the rotation of the impellers merely to prevent the impellers from grabbing articles of clothing in the wash. The arcuate surfaces of the ridges do not have a gradual changing rate of curvature to provide gentle but forcible radial movement of clothes when rotated at relatively high speeds.